A nest-like Ni@Ni1.4Co1.6S2 electrode for flexible high-performance rolling supercapacitor device design

Herein we fabricated a series of flexible electrode materials with nickel foam as a partly self-sacrificial template by an in situ growth solvent thermal method. We synthesized a nest-like Ni@Ni3S2 electrode material with building blocks of similar to 80 nm diameter nanowires. The growth mechanism of nest-like Ni@Ni3S2 electrode materials was studied through time-dependent experiments, in which the control of material morphology was realized. Residual metal nickel in the framework bestows the as-obtained electrode materials with excellent flexibility. The nest-like Ni@Ni1.4Co1.6S2 electrode material with a similar morphology and structure to Ni@Ni3S2 was fabricated using the Ni@Ni3S2 material as the template by a Co-exchange method. Continuous transition from Ni3S2 to Co9S8 was achieved depending on different replacement times. The synergistic and complementary advantageous effects of Co and Ni ions enhanced the specific capacitances from 89 F g(-1) (Ni@Ni3S2) to 122 F g(-1) (Ni@Ni1.4Co1.6S2) at a current density of 1 A g(-1) at a high loading level of similar to 20 mg cm(-2). Moreover, the cycle stability and coulombic efficiency of the Ni@Ni3S2 electrode material were also increased by the introduction of Co ions. All the as-assembled Ni@Ni3S2 and Ni@Ni1.4Co1.6S2//activated carbon supercapacitor devices possessed high energy and power density, suggesting their potential application in high-performance flexible asymmetric rolling supercapacitor devices.